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(Stroke. 2009;40:e313.)
© 2009 American Heart Association, Inc.

Advances in Stroke 2008

Advances in Imaging

From the Max Planck Institute for Neurological Research (W.D.H.), Cologne, Germany; and the Massachusetts General Hospital and Harvard Medical School (A.G.S.), Boston, Mass.

Correspondence to Prof Dr W.-D. Heiss, Max Planck Institute for Neurological Research, Gleueler Str. 50, 50931 Köln, Germany. E-mail wdh@nf.mpg.de

Key Words: imaging • advances

An extract of the first 250 words of the full text is provided, because this article has no abstract.

Imaging is still playing a major role in acute stroke management, stroke recovery, and stroke prevention. Each of these areas continued to see marked activity in the imaging field over the past year; this review will focus just on the first of these because of space constraints. With the need of more effective therapies for acute ischemic stroke, the search for a clinically applicable and reliable method to detect functionally impaired but still viable and potentially salvageable tissue—aka the penumbra—continues. Positron emission tomography using ¹⁵O-tracers still represents the best available method for the identification of brain regions with reduced cerebral metabolic rate of oxygen use (CMRO₂) that are thought to distinguish them from the ischemic core where oxygen extraction and use is greatly diminished. The mismatch between perfusion-weighted and diffusion-weighted imaging (PW–DWI) signals provides an estimate of the extent of the penumbra, but as shown in a comparative study, the volume of mismatch often is not in agreement with the volume of increased oxygen extraction fraction.¹ This resulting overestimation of the volume of the penumbra, as identified by PET, is partly due to reversibility of diffusion-weighted changes but more importantly to inaccuracies in the assessment of perfusion values. In order to overcome controversies on the best approach to quantify the penumbra by MR methods, a roadmap has been proposed² which seeks to standardize perfusion and penumbral imaging techniques, to validate the accuracy and clinical use of imaging markers of the ischemic penumbra, to validate the imaging biomarkers relevant to . . . [Full Text of this Article]